GIFT  Of 


No.  1698 


INSTRUCTIONS  FOR  MOUNTING, 
USING,  AND  CARING  FOR 

2-INCH  MORTAR  CARRIAGES 

MODEL  OF  1891 

FOR  MOUNTING 
CAST-IRON  MORTARS,  MODEL  OF  1886 

AND 

STEEL  MORTARS,  MODEL  OF  1890 


(SIX  PLATES) 


OFTHJS 

APRIL  19,  1904  ' 
REVISED  DECEMBER  42,7X909 
REVISED  APRIL  21,  1917 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1917 


No.  1698 


M.S.  Orel  no  no*-     e/efT. 

INSTRUCTIONS  FOR  MOUNTING, 
USING,  AND  CARING  FOR 

12-INCH  MORTAR  CARRIAGES 

MODEL  OF  1891 

FOR  MOUNTING 
CAST-IRON  MORTARS,  MODEL  OF  1886 

AND 

STEEL  MORTARS,  MODEL  OF  1890 


(SIX  PLATES) 


APRIL  19,  1904 

REVISED  DECEMBER  22,  1909 
REVISED  APRIL  21,  1917 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1917 


Os 


WAS  DEPABTMENT, 
OFFICE  OF  THE  CHIEF  OF  OBDNANCE, 

Washington,  April  21,  1917. 

This  manual  is  published  for  the  information  and  government  of  the  Regular 
Army  and  National  Guard  of  the  United  States. 
By  order  of  the  Secretary  of  War : 

WILLIAM  CBOZIEB, 

Brigadier  General,  Chief  of  Ordnance. 
(3) 


36210o 


LIST  OF  PLATES. 
Plate.  Drawing  No. 

I.  Side  elevation 12-5-1 

II.  Front  elevation .__  12-5-2 

III.  Plan 12-5-3  • 

IV.  Method  of  controlling  the  energy  of  recoil 15-0-7 

V.  Shot  hoist  details___^________ 12-5-16 

VI.  Shot  truck,  type  12ME 12-5-34 

(4) 


INSTRUCTIONS  FOR  MOUNTING,  USING,  AND  CARING  FOR 
12-INCH  MORTAR  CARRIAGES,  MODEL  OF  1891. 


[The  points  in  italics  are  of  importance  or  concern  the  safety  of  the  carriage 
and  should  be  specially  noted.  The  important  changes  in  this  pamphlet 
are  shown  in  boldface  type.] 


GENERAL    DESCRIPTION. 

Tliis  carriage  was  originally  designed  to  mount  the  cast-iron,  steel- 
hooped  mortar.  It  is,  however,  used  for  mounting  both  this  and  the 
all-steel  mortar. 

This  pamphlet  describes  the  carriages  for  the  cast-iron,  steel- 
hooped  mortar  at  this  date,  including  the  modifications  made  subse- 
quent to  their  original  issue.  It  applies  equally  well  to  those  on 
which  the  all-steel  mortar  is  mounted,  with  the  exceptions  noted  in 
a  subsequent  paragraph. 

The  principal  parts  of  this  carriage  are  the  base  ring,  racer,  azi- 
muth circle,  traversing-roller  system,  side  frames  and  cross  transom, 
trunnion  carriages,  recoil  and  counter  recoil  system,  elevating  system, 
traversing  system,  loading  apparatus,  shot  truck,  and  firing  apparatus. 

BASE  RING. 

The  base  ring  is  made  of  cast  iron  No.  2  in  one  piece.  It  is  bolted 
to  the  concrete  foundation  by  twelve  IJ-inch  foundation  bolts  through 
the  interior  and  twelve  through  the  exterior  flange.  The  outer  sur- 
face is  finished  to  a  diameter  of  13  feet  3^%  inches  to  form  the  pintle 
surface.  The  lower  traversing-roller  path  is  formed  on  its  upper  sur- 
face, and  to  its  inner  surface  is  bolted  the  traversing  rack. 

RACER. 

The  racer  is  made  of  gun  iron  in  one  piece  165".5  in  diameter.  Its 
lower  surface  is  finished  to  form  the  upper  path  for  the  traversing 
rollers;  a  flange  extending  down  over  the  base  ring  is  accurately 
finished  inside  to  form  a  pintle  surface.  The  diametral  pintle  clearance 
is  one-sixteenth  inch.  A  dust  guard  of  three-sixteenths  inch  sheet 
iron  11  j  inches  wide  is  secured  to  the  inner  side  of  the  racer  by  means 

(5) 


of  bolts,  in  order  to  protect  the  roller  paths  and  traversing  rollers 
from  dirt.  A  removable  floor  plate  of  cast  iron  is  bolted  across 
the  rear  of  the  opening  in  the  racer  to  permit  ready  access  to  the 
breech  of  the  mortar. 

An  iron  ladder  for  climbing  in  and  out  of  the  pit  is  bracketed  to 
the  racer  in  front  of  this  floor  plate. 

AZIMUTH  CIRCLE. 

The  azimuth  circle  is  a  brass  strip  one-fourth  inch  in  thickness 
attached  by  countersunk  screws  to  an  index  ring  of  cast  iron  made  in 
eight  sections.  The  index  ring  is  supported  in  place  around  the  racer 
by  means  of  eight  vertical  index  ring  brackets  which  are  bolted  to  the 
racer  and  by  sixteen  horizontal  angle  irons,  the  outer  ends  of  which 
are  embedded  in  the  concrete  of  the  emplacement. 

These  angle  irons  with  the  index  ring  form  supports  and  means  of 
attachment  for  the  sixteen  floor  plates  which,  with  the  concrete  floor 
of  the  emplacement,  constitute  the  working  platform.  Four  holes  are 
drilled  through  these  floor  plates  and  lifting  hooks  are  provided  for 
lifting  them  from  place.  The  azimuth  circle  is  graduated  to  degrees 
which  are  numbered  after  the  carriage  is  mounted.  An  azimuth 
pointer  graduated  to  hundredths  of  one  degree  is  attached  to  the  rear 
side  of  the  racer  by  means  of  two  screws.  The  slots  for  these  screws 
in  the  pointer  permit  of  adjustment  in  orientation.  When  this  has 
been  done,  the  pointer  should  then  be  secured  in  place  by  dowel  pins. 

TRAVERSING  ROLLER  SYSTEM. 

The  racer  rests  on  a  circle  of  twenty- four  live  conical  rollers  of 
forged  steel  maintained  in  position  by  a  distance  ring.  The  distance 
ring  is  made  of  two  rings  of  wrought  iron  bolted  to  twelve  cast-iron 
separators.  These  rings  are  slotted  to  form  bearings  for  the  journals 
on  the  ends  of  the  rollers.  A  few  of  the  first  carriages  'made  have 
rollers  with  double  flanges,  but  most  of  them  have  rollers  with  an 
inner  flange  only. 

SIDE  FRAMES  AND  TRANSOM. 

To  the  top  of  the  racer  are  bolted  two  side  frames  as  cheeks,  about 
7  feet  high,  formed  to  receive  the  mortar  and  recoil  apparatus.  The 
side  frames  are  united  in  front  by  a  cross  transom  bolted  to  them 
and  to  the  racer.  A  small  balata  and  iron  buffer  is  secured  to  the 
center  of  the  cross  transom  to  limit  the  mortar  in  its  loading  position, 
and  a  stout  hickory  stop  is  secured  to  a  socket  in  its  rear  face  to  limit 
the  mortar  in  elevation.  The  limit  in  elevation  is  65°  and  the  system 
recoils  down  slides  on  the  side  frames  placed  at  an  angle  of  50°  with 
the  horizontal  plane.  These  slides  are  formed  on  the  inner  faces  of 
the  spring  cylinders  cast  in  the  side  frames. 


TRUNNION  CARRIAGES. 

The  trunnion  carriages  of  cast  steel  are  so  formed  as  to  fit  over  the 
guide  ribs  of  the  slides  and  be  supported  in  every  direction.  They 
are  3  feet  If  inches  long  and  are  provided  with  brass  bushings  for 
the  trunnions.  A  bronze  trunnion  cap  fits  over  the  mortar  trunnion 
and  an  elastic  buffer  of  balata  and  iron  plates  is  placed  between  this 
cap  and  the  cap  square  bolted  in  the  top  of  this  trunnion  carriage. 
The  upper  ends  of  the  trunnion  carriages  have  brackets  projecting 
right  and  left,  respectively,  into  the  spring  cylinders.  Spring  com- 
pression screws  are  screwed  into  each  of  these  brackets.  These  bear 
on  hard  steel  washers  and  thus  transfer  the  weight  of  the  mortar  to 
the  spring  columns. 

RECOIL  AND  COUNTER  RECOIL  SYSTEM. 

The  spring  cylinders  cast  in  the  side  frames  are  9.6  inches  in 
interior  diameter  and  have  the  same  inclination  as  the  slides.  They 
are  slotted  on  the  inside  between  the  guide  ribs  to  allow  the  trunnion 
carriage  brackets  to  move  the  full  length  of  possible  recoil,  which  is 
2  feet  6  inches.  Although  the  above  slots  permit  it,  the  recoil  should 
not  be  more  than  20  inches  for  the  cast-iron  mortar  and  22f  inches 
for  the  steel  mortar  when  full  service  charges  are  used. 

Small  buffers  of  balata  and  iron  are  secured  in  each  slide  at  the 
limit  of  recoil  of  the  trunnion  carriages.  The  spring  cylinders  cast 
in  the  side  frames  are  not  sufficiently  long  to  accommodate  the 
requisite  number  of  springs;  they  are  therefore  extended  downward 
by  means  of  gun-iron  cylinders  secured  to  the  side  frame  by  flanges 
and  bolts.  Supporting  brackets  bolted  to  the  racer  are  provided  to 
prevent  lateral  vibration. 

Each  column  of  the  counter  recoil  springs  for  the  cast-iron  mortar 
consists  of  11  double-coil  spiral  springs  separated  from  each  other  by 
sheet-iron  disks.  The  inner  and  outer  coils  are  oppositely  wound. 
The  springs  for  the  steel  mortar  are  similar  to  the  above  except  that 
the  upper  double  coil  in  each  column  is  replaced  by  a  short  column 
of  8J  pairs  of  Belleville  springs. 

The  work  required  to  compress  the  springs  is  not  nearly  so  great 
as  the  energy  of  recoil  of  the  mortar  down  the  slides;  therefore  two 
recoil  cylinders  are  secured  to  the  side  frames  and  to  the  exterior  of 
the  spring  cylinders. 

The  recoil  cylinders  are  of  cast  steel,  T|  inches  in  interior  diameter, 
and  are  fitted  with  3J-inch  steel  piston  rods  working  through  stuffing 
boxes  at  each  end  of  the  cylinder.  The  upper  end  of  each  rod  is 
keyed  to  a  socket  in  the  trunnion  carriage  directly  below  the  trun- 
nions, while  about  the  middle  of  the  rod  a  piston  head  is  formed, 
forged  out  of  the  solid.  This  piston  has  a  bronze  bushing  and  is  an 
easy  fit  in  the  cylinder. 


8 

A  connecting  passage  is  formed  between  the  ends  of  each  cylinder, 
entering  the  upper  end  immediately  below  the  stuffing  box,  and  holes 
0.7  inch  in  diameter  are  bored  at  proper  intervals  connecting  this 
passage  with  the  cylinder. 

When  the  mortar  is  fired,  it,  together  with  the  trunnion  carriages, 
recoils  down  the  slides,  forces  the  pistons  through  their  cylinders 
and  compresses  the  spiral  springs.  Part  of  the  energy  of  recoil  is 
absorbed  by  the  resistance  of  these  springs,  but  the  greater  portion  is 
absorbed  by  the  resistance  which  the  oil  in  the  cylinders  offers  when 
it  is  forced,  from  below  to  above  the  piston  head  through  the  holes 
joining  the  connecting  passage  and  the  large  cylinder.  The  general 
movement  of  the  piston  and  the  oil  is  shown  on  PI.  IV. 

In  any  hydraulic  brake  the  resistance  is  greater  as  the  velocity  of 
the  piston  is  greater  and  as  the  openings  for  the  passage  of  the  liquid 
are  less.  The  velocity  of  retarded  recoil  of  the  mortar  being  variable 
and  a  constant  resistance  being  desired,  the  orifices  are  varied  in  such 
a  manner  that  the  relation  between  the  velocity  and  the  area  of  the 
orifices  is  at  all  points  such  as  to  give  a  nearly  constant  resistance. 

Th'ese  cylinders  are  provided  with  an  arrangement  of  throttling 
plugs  which  partially  close  the  holes  connecting  the  recoil  cylinders 
with  their  connecting  passages.  The  amount  of  closure  produced  by 
each  plug  is  stamped  on  its  end.  The  effective  area  of  orifice  at  any 
point  of  recoil  is  the  clearance  around  the  piston  head  plus  the  ef- 
fective area  of  all  the  holes  not  passed  over  by  the  piston  in  its 
recoil.  PI.  IV  shows  how  these  orifices  are  successively  cut  off  by 
the  piston  in  its  movement.  By  this  arrangement  the  area  of  the 
orifice  of  flow  at  any  point  of  recoil  has  such  a  relation  to  the  veloc- 
ity of  recoil  at  that  point  as  to  give  a  nearly  constant  resistance  to 
the  motion  of  the  piston.  This  results  in  a  nearly  constant  fluid  pres- 
sure. The  areas  of  orifices  have  to  be  calculated  for  a  particular  set 
of  loading  conditions.  The  conditions  used  are  those  that  obtain 
with  the  maximum  service  charges.  Smaller  charges  will  result  in 
somewhat  shorter  recoils  than  with  full  charges. 

The  upper  face  of  the  piston  is  recessed,  and  into  this  recess  fits  an 
annular  projection  from  the  upper  bronze  cylinder  head.  When  the 
pistons  have  reached  the  limit  of  recoil,  the  springs  return  the  mortar 
to  the  firing  position.  Near  the  end  of  this  return  to  the  firing  posi- 
tion the  annular  projection  of  the  cylinder  head  enters  the  recess  in 
the  piston  head.  The  oil  caught  in  this  recess  can  escape  but  slowly 
through  the  small  clearance,  and  thus  the  recoiling  parts  are  brought 
gradually  to  rest. 

The  lower  or  pressure  ends  of  the  recoil  cylinders  are  connected  by 
an  equalizing  pipe  so  that  the  pressure  in  both  cylinders  is  always  the 
same. 


Should  the  equalizing  pipes  break  or  become  unserviceable  they 
may  be  removed  and  the  carriage  continued  in  service,  the  holes 
tapped  in  the  lower  ends  of  the  cylinders  for  the  equalizing  pipes 
being  filled  by  bronze  plugs  kept  on  hand  for  this  purpose. 

Lateral  guides  of  gun  iron  are  secured  to  the  side  frames  and 
adjusted  so  as  to  bear  against  the  body  of  the  mortar  at  its  breech 
end.  By  this  means  any  tendency  to  move  out  of  the  vertical  plane 
is  counteracted. 

Each  cylinder  is  provided  with  a  filling  plug,  and  an  emptying 
plug  is  placed  in  the  coupling  of  the  equalizing  pipe.  In  -filling  the 
filing  plugs  should  be  removed  from  both  cylinders  so  as  to  permit 
the  air  to  escape  and  thus  insure  the  filling  of  both  cylinders  up  to 
the  filling  holes.  The  cylinders  should  be  filled  to  overflowing  for 
all  charges  with  a  neutral  oil  of  0.85  specific  gravity,  such  as  the 
hydroline  in  service.  A  denser  oil  would  increase  the  pressure  in  the 
cylinders  slightly  and  also  shorten  the  recoil  somewhat.  It  requires 
about  10J  gallons  to  completely  fill  both  cylinders. 

If  it  is  desired  to  measure  the  recoil,  it  can  be  done  on  the  piston 
rods  by  making  several  turns  around  them  with  twine  or  wire  and 
tying  it  very  tightly  just  where  the  piston  rod  enters  the  stuffing  box. 
The  height  of  the  twine  above  the  stuffing  box  after  firing  will  indi- 
cate the  counter  recoil,  which  will  also  be  the  recoil  if  the  mortar  was 
returned  to  the  firing  position.  There  is  a  rack  on  each  side  of  the 
frame  for  the  purpose  of  embarring  the  mortar  up  to  the  firing  posi- 
tion provided  the  springs  do  not  return  it.  If  it  is  shown  that  the 
springs  are  weak,  remove  the  spring-cylinder  caps  and  screw  down  the 
adjusting  screws  an  amount  equal  to  the  distance  that  the  trunnion 
carriages  are  below  the  firing  position.  If,  after  the  next  round,  the 
springs  do  not  return  the  mortar  to  the  firing  position,  repeat  the 
above  operation ;  but  the  total  compression  by  means  of  the  adjusting 
screws  should  not  be  more  than  3  inches. 

ELEVATING  SYSTEM. 

The  elevating  gear  consists  of  two  bronze  circular  racks,  one  on 
each  side  of  the  mortar,  secured  by  brackets  to  the  mortar  and  to  a 
hoop  shrunk  onto  the  mortar  just  in  front  of -the  reinforcing  hoops. 
Each  rack  is  actuated  by  means  of  a  handwheel  and  spur  gearing 
attached  to  the  trunnion  carriage.  One  of  the  gear  wheels  may  be 
graduated  on  its  face  and  an  index  attached  to  the  carriage  will  en- 
able the  degrees  of  elevation  to  be  read. 

The  pinion  of  each  handwheel  has  a  conical  surface  on  its  inner  end 
which  fits  against  a  similar  surface  on  the  elevating  gear  bracket.  By 
screwing  up  on  a  nut  on  the  elevating  handwheel  shaft,  these  sur- 
faces may  be  clamped  together  and  the  mortar  held  in  either  the  load- 
94530—17 2 


10 

ing  or  the  firing  position.  By  this  means  the  desired  amount  of  fric- 
tion can  be  obtained  and  undue  strains  on  the  teeth  of  the  elevating 
racks  and  pinions,  due  to  a  tendency  of  the  mortar  to  change  its  eleva- 
tion in  recoil  and  counter  recoil,  are  avoided.  In  the  earlier  carriages 
this  clamp  nut  is  provided  with  two  handles  by  which  it  may  be 
screwed  up.  In  the  later  carriages  these  handles  are  omitted  and  the 
nuts  are  set  up  by  wrenches  hung  by  chains  to  the  side  frames. 

TRAVERSING  SYSTEMS. 

A  circular  traversing  rack  of  cast  iron  No.  2  is  bolted  to  the 
inner  surface  of  the  base  ring.  A  shrouded  pinion  of  bronze  gears 
into  this  rack  and  is  itself  keyed  to  a  vertical  shaft  which  is  supported 
by  a  bracket  bolted  to  the  inner  side  of  the  right  side  frame.  The 
upper  end  of  the  shaft  carries  a  worm  wheel  of  bronze  geared  into  a 
worm  of  steel  on  a  horizontal  shaft  which  passes  through  both  side 
frames.  This  shaft  is  provided  with  bearings  in  brackets  bolted  to 
the  side  frames.  Power  for  traversing  is  applied  to  this  shaft  by 
means  of  crank  handles  at  both  ends.  The  traversing  shaft  is  pro- 
vided with  oil  tubes  and  plugs  for  the  convenient  oiling  of  all  bear- 
ings, and  an  oil  tube  at  the  front  of  the  racer  is  provided  for  oiling 
the  pintle  surface.  For  the  proper  oiling  of  this  surface  it  is  neces- 
sary to  traverse  the  carriage  entirely  around  during  the  operation 
of  oiling. 

LOADING  APPARATUS. 

The  loading  apparatus  consists  of  a  shell  scoop,  carried  on  the  end 
of  a  bow  lever,  the  lower  end  of  which  is  attached  to  a  shaft  which 
passes  through  the  left  side  frame.  This  shaft,  on  the  outside,  also 
carries  a  lever,  the  upper  end  of  which  is  fitted  with  a  swivel  nut. 
A  screw  spindle,  called  the  shell-hoist  screw,  extending  to  the  front 
of  the  carriage,  where  it  is  supported  in  a"  suitable  bearing,  works 
through  this  nut  and  carries  a  handwheel.  The  shell,  resting  in  the 
shell  tray,  is  carried  in  a  truck  which  delivers  it  direct  to  the  shell 
scoop  when  the  latter  is  depressed.  The  shell  tray  'has  trunnions 
which  bear  in  beds  on  the  trucks,  and  the  barrow  forces  these  trun- 
nions into  beds  prepared  for  them  in  the  shell  scoop.  There  are 
guides  on  the  racer  for  the  wheels  of  the  truck,  so  that  it  is  con- 
strained to  move  to  the  proper  position.  When  the  handwheel  on 
the  end  of  the  screw  spindle  is  turned,  the  shot  in  the  tray  is  raised 
to  a  proper  position  for  ramming.  After  the  shell  is  rammed,  the 
shell  tray  is  then  lowered  in  a  similar  manner  into  the  truck.  There 
are  stop  nuts  on  the  shell-hoist  screw  which  can  be  adjusted  so  as  to 
stop  the  motion  of  the  shell  scoop  when  the  projectile  is  in  the  proper 
place  for  ramming  and,  when  depressed,  to  bring  the  shell  tray  in 
M  proper  position  to  be  run  off  by  the  truck.  (The  truck  wheels  are 
provided  with  rubber  tires.) 


11 

SHOT  TRUCKS. 

Forty-one  of  these  carriages  have  been  altered  for  direct  loading 
by  means  of  shot  trucks,  type  12ME,  Plate  VI.  The  truck  is 
equipped  with  a  hydraulic  stop  and  a  brake.  For  loading,  the  mortar 
is  brought  to  its  position  of  minimum  elevation  and  locked  by  means 
of  the  elevating  clamp  nuts.  The  shot  truck,  aided  by  guide  rails 
on  the  racer,  is  moved  up  to  its  proper  position  at  the  breech  of  the 
mortar,  the  hydraulic  stop  on  the  truck  absorbing  any  jar  of  impact 
between  the  two.  The  brake  is  applied  holding  the  truck  at  rest 
while  the  projectile  is  being  rammed  into  place. 

FIRING  APPARATUS. 

The  mortar  may  be  fired  either  electrically  or  by  lanyard.     The 
current  for  firing  the  mortar  electrically  is  obtained  from  a  firing 
magneto. 
FIRING  MAGNETO. 

The  magneto  is  inclosed  in  a  bronze  case  and  is  provided  with  high 
ratio  gearing  and  a  lever  for  operating.  It  is  not  necessary  to  raise 
the  lever  violently,  as  a  slow  motion  is  sufficient  to  fire  the  primer. 
One  pull  of  the  lever  should  suffice  when  the  magneto  is  working 
properly.  A  clutch  is  provided  on  the  intermediate  shaft,  making  it 
possible  to  move  the  lever  back  into  its  normal  position  without  re- 
versing the  armature  shaft.  The  lever  is  held  in  its  off  position  by 
a  catch,  when  not  in  use.  For  further  information,  see  Ordnance  De- 
partment Pamphlet,  Form  No.  1814. 

LANYARD  PULL. 

In  case  the  electric  firing  system  does  not  work  properly  the  service 
lanyard  may  be  used.  In  connection  with  this  lanyard,  an  auxiliary 
lanyard  is  applied  in  order  to  provide  a  pull  on  the  friction  primer 
as  nearly  direct  as  possible  when  the  mortar  is  in  the  firing  position. 
It  has  a  hook  at  the  mortar  end  and  passes  under  a  pulley  attached 
by  a  bracket  to  the  pit  ladder  and  through  a  hole  drilled  through  the 
removable  floor  plate. 

A  lanyard  stop  attached  to  the  rear  end  of  the  auxiliary  lanyard 
fits  into  a  lanyard  washer  secured  to  the  floor  plate  and  prevents  the 
lanyard  from  falling  into  the  pit.  The  lanyard  stop  is  provided  with 
a  loop  for  the  attachment  of  the  service  lanyard. 

Carriages  for  the  steel  mortar  differ  in  the  following  respects : 

1.  Distance  pieces  are  placed  under  the  guides  (that  are  secured  to 
the  side  frames)  that  guide  the  breech  end  of  the  mortar,  and  cause 
the  mortar  to  travel  in  a  true  vertical  plane. 

2.  Distance  pieces  are  used  to  secure  the  elevating  rack  to  the 
mortar. 


12 

3.  Packing  rings  are  put  on  the  trunnions  in  order  to  take  up  the 
lateral  play  due  to  the  difference  in  width  between  the  rim  bases  of 
the  cast  iron  and  steel  mortar's. 

4.  The  brackets  that  are  bolted  to  the  mortar  and  are  used  to  brace 
the  elevating  arcs  differ  from  those  on  the  cast-iron  mortar. 

5.  The  clamping  nut  for  the  elevating  gear  is  without  the  clamping 
handles  and  is  set  up  by  means  of  a  wrench  attached  to  the  carriage. 

6.  The  buffer  located  in  the  front  transom  and  holding  the  mortar 
in  a  horizontal  position  is  longer. 

7.  The  hickory  stake  that  is  secured  in  the  front  transom  and  limits 
the  extreme  elevation  of  the  mortar  is  longer. 

8.  There  are  supporting  brackets  for  the  spring  cylinder  extension. 
NOTE. — Care  should  be  taken  by  officers  and  employees  at  the  forts 

in  ordering  parts  of  carriages  to  state  by  whom  the  carriage  (for 
which  the  parts  are  ordered)  was  manufactured  and  whether  the  car- 
riage is  for  a  steel  or  a  cast-iron  mortar.  In  ordering  conical  traverse 
rollers,  state  whether  one  or  two  flanges. 

ASSEMBLING    THE    CARRIAGE. 
IMPLEMENTS. 

The  assembling  requires  machines  and  implements  for  mechanical 
maneuvers  usually  found  at  forts,  such  as  falls,  blocking,  jacks,  slings, 
garrison  gin,  etc. 

GENERAL  REMARKS. 

The  size  of  the  carriage  is  such  that  it  must  be  partially  dismounted 
for  shipment,  so  that  when  it  arrives  at  its  destination  it  has  to  be 
assembled.  In  assembling  the  carriage,  as  in  all  machinery ',  no  parts 
should  ~be  directly  struck  with  a  steel  hammer  or  sledge.  Soft  metal 
drifts,  copper  or  lead  hammers  should  be  used.  In  unloading  or  han- 
dling the  parts  care  should  be  exercised  that  the  edges  or  finished  sur- 
faces do  not  become  upset  or  burred.  When  two  bearing  surfaces  are 
brought  together*  it  is  especially  necessary  that  both  parts  should  be 
absolutely  clean,  smooth,  and  well  lubricated. 

The  following  description  gives  a  statement  of  the  order  in  which 
the  parts  should  be  put  together : 

Base  ring. — Move  the  base  ring  to  its  position  over  the  pit  by 
means  of  skids  and  rollers.  Lower  the  ring,  by  means  of  jacks  or  a 
derrick,  into  its  position  over  the  foundation  bolts,  care  being  taken 
to  have  the  bolts  central  in  the  holes  in  the  ring.  Level  the  ring  by 
means  of  wedges  driven  under  the  flanges  near  the  foundation  bolts. 
For  leveling  use  a  machinist's  level  and  straightedge.  The  greatest 
care  should  be  taken  in  using  the  level  and  straightedge  that  the 
middle  of  the  level  is  equidistant  from  the  points  of  contact  of  the 
straightedge  with  the  surface  being  leveled,  and  that  these  points  of 


13 

contact  on  the  straightedge  are  equidistant  from  either  end.  In 
using  the  level  it  should  always  be  reversed  and  the  mean  of  tht< 
readings  in  the  two  positions  be  considered  the  true  reading.  Level 
at  first  three  points  and  then  the  intermediate  points  on  top  of  the 
roller  path.  Then  with  the  roller  path  leveling  gage  level  the  path 
radially.  When  it  shows  level  at  every  point  the  nuts  should  be 
tightened  evenly  on  the  foundation  bolts.  Caliper  the  pintle  surface. 
The  diameter  should  not  differ  by  more  than  0.01".  Again  check 
the  leveling  of  the  ring,  and  should  the  pintle  surface  still  be  eccen- 
tric, it  must  be  scraped  round ;  then  pour  grouting  under  .the  base 
ring,  care  being  taken  to  have  it  run  under  every  part  of  the  ring. 

Distance  ring  and  traversing  rollers. — Thoroughly  clean  the  lower 
roller  path  and  rollers  and  assemble  the  distance  rings  on  the  rollers ; 
then  run  the  rollers  around  several  times  by  hand  to  see  that  they 
work  properly. 

Racer. — Move  the  racer  over  its  position  on  the  base  ring,  making 
sure  that  the  roller  path  and  pintle  surfaces  are  thoroughly  clean. 
Lower  it  into  place  by  means  of  two  jacks,  each  one  engaging  on  the 
inside  upon  a  projecting  portion  jusfc  below  the  seats  for  the  side 
frames;  a  short  piece  of  timber  should  be  placed  on  top  of  each  jack. 
After  the  racer  is  lowered  to  its  proper  position,  run  it  around  by 
hand  several  times  to  see  that  it  runs  freely  and  that  the  pintle  sur- 
faces do  not  bind.  Bolt  on  the  dust  guards  to  prevent  dust  from 
getting  on  the  roller  paths  and  rollers. 

Side  frames. — If.  the  spring  cylinder  extensions,  recoil  cylinders, 
pistons,  and  trunnion  carriages  are  not  assembled  to  the  side  frames 
when  received,  they  should  be  so  assembled  before  the  side  frames 
are  put  in  place.  This  will  be  most  conveniently  done  with  the  side 
frames  in  a  horizontal  position  on  blocking.  After  the  springs  are 
compressed,  a  garrison  gin  will  be  found  convenient  for  raising  the 
side  frames  to  a  vertical  position  on  the  racer.  All  bolts  and  bolt 
holes  are  numbered  so  that  there  will  be  no  difficulty  in  locating  the 
bolts;  but  in  case  this  has  been  neglected,  the  accompanying  list  of 
parts  will  indicate  their  size  and  location. 

Spring  cylinder  extension. — This  should  be  first  bolted  to  the  side 
frame,  screwing  in  the  two  studs  first.  Attach  the  balata  buffer  to 
the  bottom  of  the  slides.  On  carriages  having  the  bracket  for  sup- 
porting the  spring  cylinder  extension,  this  bracket  should  be  bolted 
to  the  racer  before  the  side  frame  or  the  spring  cylinder  extension 
is  erected  in  place. 

Recoil  cylinder. — The  recoil  cylinder  must  be  assembled  next,  but 
before  doing  this,  clean  the  piston  rod  carefully  as  well  as  the  slides 
for  the  trunnion  carriage,  and  move  the  trunnion  carriage  on  the  slide 
to  see  that  it  works  easily.  In  assembling  this  cylinder  the  bolts 
going  through  the  side  frame  should  be  inserted  first,  and  then  those 


14 

joining  the  recoil  cylinder  to  the  spring  cylinder  extension.  Do  not, 
at  this  time,  key  the  trunnion  carriage  to  the  piston  rod,  but  see  that 
the  bronze  cylinder  head,  not  the  follower,  is  screwed  down  hard, 
and  that  the  piston  rod  is  moved  as  far  to  the  top  as  possible. 

Recoil  springs. — Remove  the  cap  of  the  spring  cylinder  and  move 
the  trunnion  carriage  on  the  slides  until  there  is  a  space  of  about  18 
inches  between  the  top  of  the  spring  cylinder  and  the  underside  of 
the  projecting  bracket;  this  space  is  required  for  the  insertion  of  the 
coiled  springs;  if  more  convenient,  the  trunnion  carriage  can  be  en- 
tirely removed  from  the  slides.  Assemble  the  springs  together,  a 
small  coil  inside  a  large  one,  and  place  the  separator  plates  on  the 
ends.  Insert  the  ends  of  the  compressor  rod:  which  is  threaded  for  a 
distance  of  about  6  feet  9  inches,  into  the  hole  in  the  bottom  of  the 
spring-cylinder  extension,  and  push  the  rod  through  until  the  end 
comes  to  the  top  of  the  spring  cylinder.  String  on  this  rod  the  end 
plate  and  the  11  coiled  springs  with  their  separator  plates,  then 
string  the  top  plate  and  the  small  washer  of  hardened  steel,  which 
has  an  annular  projection  fitting  the  hole  in  the  top  plate.  Push  the 
compressor  rod  through  the  hole  in  the  bracket  on  the  trunnion  car- 
riage, placing  the  small  cast-iron  washer  and  nut  on  top  of  the 
bracket;  on  the  bottom  of  the  rod  put  on  the  centering  washer  and 
nut. 

With  the  ratchet  wrench  furnished  with  the  carriage,  screw  down 
the  nut  on  the  top  end  of  the  rod  and  compress  the  springs  until  the 
trunnion  carriage  can  be  keyed  to  the  piston  rod.  Remove  the  com- 
pressor rod  and  cast-iron  washer.  Screw  into  the  threaded  hole  in 
the  bracket  the  steel  adjusting  screw  and  bring  it  to  bear  hard  enough 
on  the  hardened  washer  to  make  clearance  between  the  washer  and 
the  bracket. 

There  is  a  curved  surface  under  the  projecting  arm  of  the  trunnion 
carriage  which  sometimes  bears  hard  on  the  top  plate  and  forces  it 
sideways  so  that  it  is  difficult  to  make  it  enter  the  spring  cylinder. 
This  can  be  overcome  by  putting  pieces  of  iron  between  the  projecting 
arm  and  the  top  plate  and  removing  these  pieces  when  the  adjusting 
screw  is  brought  to  bear  on  the  spring  columns.  When  assembled, 
the  small  washer  prevents  the  top  plate  from  striking  the  curved  sur- 
face of  the  arm.  Bolt  on  the  spring  cylinder  cap.  Lift  the  side  frame 
to  a  vertical  position  and  bolt  to  the  racer.  The  turned  tap  bolts  go 
through  the  holes  which  are  1J  inches  in  diameter,  i.  e.,  the  two  front 
and  two  rear  holes,  and  should  be  put  in  first.  The  rough  bolts  go 
into  the  holes  which  are  !•£$  inches  in  diameter. 

The  springs  can  be  compressed  after  the  side  frame  is  bolted  to  the 
racer.  This  requires  that  the  compressor  rod  be  inserted  from  the  top 
through  the  hole  in  the  bracket  on  the  trunnion  carriage  after  all  the 


15 

springs  have  been  put  into  the  spring  cylinder.  But  there  is  some- 
times difficulty  in  inserting  the  lower  end  of  the  rod  through  the  holes 
in  the  separator  plates  and  especially  through  the  hole  in  the  bottom 
plate. 

It  will  be  most  convenient  to  pack  the  stuffing  boxes  when  the  side 
frames  are  in  the  horizontal  position,  using  Garlock's  five-eighths 
hydraulic  packing  for  this  purpose. 

MOUNTING   THE   MORTAR. 

If  the  mortar  is  to  be  mounted  by  means  of  blocking,  it  will  be 
found  more  convenient  to  do  it  before  the  transom  is  assembled.  If 
the  mortar  is  to  be  mounted  by  means  of  a  derrick,  the  transom  can 
be  assembled  first.  To  mount  the  mortar  with  blocking,  build  a  run 
of  blocking  in  front  of  the  carriage  at  such  a  height  that  the  trun- 
nions of  the  mortar  will  just  clear  the  front-top  edges  of  the  trunnion 
slide.  Pull  the  mortar  in  until  the  trunnions  can  enter  the  channels 
of  the  trunnion  carriages,  then,  by  means  of  jacks,  lower  and  move  it 
into  position,  care  being  taken  that  the  bearings  are  not  bruised  or 
jammed.  Pieces  of  hard  wood  may  be  used  on  each  side  to  guide  the 
trunnions  at  the  point  where  they  reach  the  bronze  bushings.  With 
the  steel  mortar  the  packing  rings  must  be  placed  over  the  trunnions 
before  the  mortar  is  lowered  into  the  trunnion  carriages.  After  the 
mortar  is  down,  assemble  the  trunnion  caps,  insert  the  balata  and  iron 
buffers  and  bolt  on  the  cap  squares.  Place  the  transom  in  position 
and  bolt  to  side  frames. 

TRAVERSING  GEAR. 

Bolt  the.  worm-wheel  box  to  the  right  side  frame  and  push  up 
through  its  bearing  the  vertical  traversing  shaft  until  there  is  room 
to  bolt  the  lower  bracket  to  the  racer,  being  careful  to  assemble  the 
sleeve  between  the  two  brackets.  Hold  the  shrouded  pinion  in  place 
and  lower  the  shaft  through  the  lower  bracket  and  pinion  and  put  on 
the  worm  wheel.  Push  the  worm  shaft  with  worm  attached  through 
the  worm-wheel  box  from  the  right  and  screw  the  worm  in  place, 
placing  the  middle  bearing  on  the  shaft  before  it  passes  through  the 
left  side  frame.  Assemble  the  three  bearings  for  the  shaft.  Assemble 
the  equalizing  pipes  and  fill  cylinders  with  oil. 

AZIMUTH  CIRCLE. 

Bolt  the  index  ring  brackets  to  the  base  ring.  Bolt  the  sections  of 
the  index  ring  to  these  brackets  and  to  the  angle  iron  supports. 
Level  the  angle  iron  supports  and  set  the  outer  ends  in  the  concrete 
platform.  Put  on  floor  plates,  pit  ladder,  etc.,  and  secure  them  in 
place. 


16 

ELEVATING  GEARING. 

Bolt  the  elevating  gearing  to  the  trunnion  carriages,  and  after  the 
brackets  have  been  secured  to  the  mortar,  the  elevating  rack  can  be 
bolted  to  them  and  to  the  elevating  band. 

LOADING  TRAY. 

Put  the  shaft  for  the  loading  arm  through  the  left  side  frame  and 
key  to  it,  on  the  outside,  the  arm  with  the  swivel  nut.  If  necessary 
remove  the  nuts  from  the  end  of  the  shell  hoist  screw  and  screw  this 
end  through  the  swivel  nut.  Put  the  swivel  bearing  with  the  large 
end  to  the  front  and  its  accompanying  bushing  and  collar  onto  this 
shaft  and  bolt  the  bracket  for  this  bearing  to  the  left  side  frame. 
Attach  handwheel  and  nut.  Lay  the  loading  arm  on  the  floor  plate, 
lifting  up  the  end  for  the  shaft  and  holding  it  against  the  shaft,  at 
the  same  time  turning  the  handwheel  until  the  key  and  keyway  come 
together.  Then  push  the  arm  on  the  shaft  and  put  in  the  pin. 
Assemble  the  shell  scoop  and  adjust  it  by  means  of  the  screw  and  nut. 
The  guides  for  the  shell  barrow  can  now  be  attached  and  also  the 
azimuth  pointer. 

CARE  OF  THE  CARRIAGE. 

Carriages  should  be  traversed  from  time  to  time  throughout  their 
entire  movement.  The  mortar  will  be  habitually  elevated  so  that  it 
will  be  parallel  to  the  piston  rod  and  the  breech  cover  left  off.  The 
translating  roller  will  be  left  in  place.  At  posts,  where  the  sand  blows 
onto  the  breech  mechanism  and  at  all  posts  during  the  cold  season 
when  snow  and  ice  may  collect  and  form  around  the  breech  mecha- 
nism, the  mortar  will  be  kept  horizontal,  with  the  breech  cover  on. 
The  mortar  should,  however,  from  time  to  time,  when  not  in  use,  be 
elevated  and  depressed  throughout  its  range  of  movement. 

It  is  especially  required  that  all  parts  of  carriages  be  kept  free 
from  rust  at  all  times.  If  this  be  allowed  to  accumulate  its  removal 
from  all  bearing  parts,  and  especially  piston  rods,  requires  particular 
attention  in  order  that  the  clearances  shall  not  be  unduly  increased. 
The  use  of  sandpaper  for  this  purpose  is  forbidden  and  emery  cloth 
No.  1,  being  coarse  enough  for  any  ordinary  rusting,  should  be  used, 
the  rust  being  softened,  if  necessary,  by  kerosene. 

CARE  OF  EECOIL  CYLINDERS. 

The  recoil  cylinders  should  be  kept  filled  with  hydroline  oil  of 
specific  gravity  of  about  0.85  at  all  times — as  full  as  the  location  of 
the  filling  holes  will  permit.  If  leakage  occurs  from  the  recoil  sys- 
tem it  should  be  immediately  remedied,  calling,  if  necessary,  upon 
the  district  armament  officer  for  the  services  of  skilled  labor. 


17 

The  repacking  of  stuffing  boxes  may  be  done,  if  necessary,  by 
trained  enlisted  men  under  the  supervision  of  an  officer,  but  will 
preferably  be  done  by  skilled  labor,  as  follows : 

To  PACK  A  STUFFING  Box. 

Draw  the  oil  from  the  cylinder ;  unscrew  the  follower  and  take  out 
the  gland.  For  this  purpose  special  extractors,  consisting  of  iron 
rods  threaded  at  one  end,  are  furnished  with  each  carriage.  All  of 
the  old  packing  should  now  be  removed,  using  for  the  purpose  the 
packing  extractors  provided  for  this  purpose.  This  extractor  consists 
of  a  bronze  cage  fitting  around  the  piston  rod  and  provided  on  one 
end  with  several  hooks  which  engage  in  the  packing  when  forced 
against  it  and  rotated  counterclockwise.  The  cage  is  provided  with 
notches  on  opposite  sides  into,  which  pinch  bars  may  be  engaged  if 
necessary  and  the  packing  withdrawn  until  it  reaches  the  threads  of 
the  stuffing  box.  From  this  point  the  packing  is  withdrawn  by 
turning  the  extractor  in  a  counterclockwise  direction  until  packing 
is  entirely  removed.  This,  method  avoids  injuring  the  packing  by 
drawing  it  across  the  threads.  The  extractor  is  provided  with  han- 
dles by  which  to  rotate  it  and  is  made  in  halves  hinged  together  so. 
that  it  may  be  readily  applied  to  or  removed  from  a  piston  rod. 

The  old  packing  should  be  examined  and  all  unfit  for  use  discarded. 
If  any  of  it  is  again  used,  it  should  be  put  in  after  the  new. 

To  repack,  put  on  the  piston  rod  one  ring  of  0.625-inch  Garlock's 
"  waterproof  hydraulic  "  packing  and  force  it  well  to  the  bottom  of 
the  stuffing  box  by  a  wooden  stick  and  mallet.  Treat  each  layer  of 
packing  until  five  rings  of  new  packing  have  been  inserted,  or  an 
equal  amount  of  new  and  old  when  any  of  the  latter  is  used.  Care 
should  be  taken  to  break  joints  of  the  packing;  that  is,  the  joint  of 
each  ring  as  inserted  should  be  on  the  opposite  side  of  the  piston  rod 
from  the  one  preceding  it. 

Clean  out  from  the  screw  threads  all  the  particles  of  the  packing 
that  have  caught  in  them,  push  in  the  gland  and  screw  up  the  fol- 
lower. No  more  force  should  ~be  used  on  the  spanner  wrench  than  that 
of  two  men,  and  generally  that  of  one  man  is  sufficient.  The  addition 
of  a  pipe  to  the  end  of  the  spanner  wrench  should  not  be  permitted. 
When  the  box  is  properly  filled  and  the  follower  tightened  there 
should  not  be  more  than  three-fourths  of  an  inch  of  space  between 
the  flange  of  the  follower  and  the  piece  into  which  the  follower  is 
screwed.  The  follower  should  be  tightened  from  time  to  time.  If 
the  follower  is  screwed  into  the  stuffing  box  too  tightly  an  unneces- 
sary amount  of  friction  will  be  produced  on  the  piston  rod.  When 
the  follower  is  screwed  in  until  the  flange  strikes  the  box,  another 
ring  of  packing  should  be  inserted. 

It  is  to  be  expected  that  a  slight  amount  of  oil  will  soak  through 
and  drip  from  the  boxes  of  carriages  when  not  in  use.  Also  when 


18 

tightening  the  followers  a  slight  amount  of  oil  will  squeeze  out  of 
the  saturated  packing.  This  oil  should  be  caught  and  not  allowed  to 
render  the  carriage  unsightly. 

Recoil  cylinders  should  be  emptied  at  least  once  in  every  three 
months  and  thoroughly  cleaned  once  every  six  months  or  oftener  if 
their  condition  requires  it.  For  cleaning  these  cylinders  a  plumber's 
hand  force  pump  will  be  supplied  each  coast  artillery  post.  The 
pump  should  have  a  suction  hose  about  10  feet  and  a  rubber  dis- 
charge tube  about  15  feet  in  length.  The  following  method  will  be 
followed  in  cleaning  the  recoil  cylinder. 

To  CLEAN  RECOIL  CYLINDERS. 

(a)  Remove  the  oil  from  the  cylinders  through  the  drain  hole  in 
the  emptying  coupling. 

(&)  Remove  all  throttling  and  filling  plugs  from  each  recoil  cyl- 
inder and  the  plugs  in  both  ends  of  the  by-pass  cylinders  and  the 
equalizing  pipe. 

(<?)  Place  a  receptacle  containing  about  3  gallons  of  kerosene  oil 
under  the  lower  end  of  a  by-pass  cylinder.  Insert  the  suction  hose  in 
the  receptacle  and  forcibly  inject  the  oil  into  the  by-pass  cylinder 
until  it  is  thoroughly  cleaned.  Remove  all  sediment,  dirt,  etc.,  from 
the  recoil  cylinder  by  forcibly  injecting  the  oil  into  the  filling  hole 
and  then  into  each  throttling  plug  hole  in  turn  from  the  top  down- 
ward. The  rubber  tube  should  be  inserted  into  the  cylinder  through 
each  hole.  Clean  both  cylinders  on  the  other  side  in  a  similar  man- 
ner. Allow  the  kerosene  oil  to  drain  out  of  the  system.  The  equal- 
izing pipe  should  also  be  cleaned  with  the  force  pump. 

(d)  Assemble  the  equalizing  pipe  and  replace  all  plugs,  taking 
care  that  each  throttling  plug  is  inserted  in  its  correct  hole  in  order 
that  the  recoil  will  be  properly  controlled. 

All  parts  that  have  been  dismounted  should  be  carefully  inspected 
to  insure  that  each  has  been  correctly  and  properly  assembled. 

It  will  be  observed  that  it  is  not  necessary  to  remove  the  packing 
from  the  stuffing  boxes  to  clean  the  cylinders.  After  the  cylinders 
have  been  cleaned  and  the  parts  reassembled,  the  cylinders  should  be 
immediately  filed  with  the  hydroline  oil  furnished  ~by  the  Ordnance 
Department  for  that  purpose. 

Lubrication,  etc. — When  the  carriage  is  to  be  kept  in  readiness  for 
service,  and  is  in  daily  or  frequent  use,  all  bearing  parts  must  be  kept 
thoroughly  cleaned  and  lubricated.  Especial  attention  should  be 
given  to  the  lubrication  of  the  gun  trunnions,  rollers,  pintle  surfaces, 
shaft  bearings,  and  sliding  surfaces,  trunnion  carriage  guides,  ele- 
vating and  traversing  mechanisms,  and  the  teeth  of  all  gears.  The 
above  parts  should  ~be  lubricated  at  frequent  intervals,  whether  tkv 
carnage  is  maneuvered,  or  not.  and  it  is  essential  for  the  proper  pres- 


19 

ervation  and  working  of  the  carriage  that  on  every  day  on  which  it 
is  to  be  maneuvered  for  any  purpose  all  bearings  should  be  well  lubri- 
cated immediately  before  such  maneuvering.  Proper  lubricating 
and  cleaning  of  the  traversing  rollers  and  their  paths  are  essential 
to  free  working  of  the  carriage.  The  dust  guards  may  be  removed 
to  oil  the  traversing  rollers,  or  to  clean  them  and  their  paths.  An 
oil  pipe  is  provided  on  the  front  of  the  racer  for  oiling  the  pintle 
surface.  Oil  should  be  poured  into  this  pipe  and  the  carriage  trav- 
ersed around  several  times  so  that  all  parts  of  the  pintle  surface  may 
be  oiled.  All  oil  holes  are  provided  with  bronze  oil  plugs.  Oil  holes 
when  provided  must  be  cleaned  out  frequently  to  keep  them  free 
from  sand  and  grit  and  will  habitually  be  kept  closed  by  the  screw 
plugs  provided,  except  when  in  the  act  of  oiling.  Before  oiling  at 
any  oil  hole  wipe  off  carefully  Uny  dirt  or  grit  near  the  opening  that 
might  be  carried  doivn  into  the  bearing  by  the  oil. 

CONDITION  IN  ORDINARY  (NOT  EEADY  FOR  IMMEDIATE  SERVICE). 

If  the  carriage  is  to  remain  unused  for  a  short  interval,  all  bright 
and  bearing  parts  should  be  covered  with  a  coating  of  light  slushing 
oil.  The  rollers  and  roller  paths  should  be  cleaned  and  covered  with 
this  oil,  and  the  space  between  the  dust  guard  and  racer  should  be 
filled  with  waste  to  keep  out  the  dust.  Experience  has  indicated  that 
the  oil  should  not  be  removed  from  the  recoil  cylinders  when  car- 
riages are  to  be  unused  for  a  considerable  period,  as  the  walls  of  the 
cylinders  soon  become  dry  and  rust. 

PAINTS,  OILS,  ETC.  ' 

For  information  regarding  paints,  oils,  cleaning  materials,  and 
methods  of  using  same,  see  Ordnance  Department  pamphlet  Form 
No.  1869. 

SPARE    PARTS    FOR    CARRIAGE. 

The  following  spare  parts  for  12-inch  breech  loading  mortar  car- 
riages, model  of  1891,  are  issued  to  the  service  for  each  four  carriages 
per  post : 

1  set  filling  plugs. 

1  ratchet  spring  for  spring  compres- 
sion screw  wrench. 

$  set  oil-hole  plugs. 

1  set  taper  pins. 

i  set  screws  for  floor  plates  per  each 
model  of  carriage. 

1  set  dust  guard  bolts  per  each  model 
of  carringe. 

i  set  rivets  for  same. 

1  set  azimuth  pointers  with  screws. 


1  set  felt  buffers,  complete,  and  metal 
separators,  12-inch  mortar  carriage, 
model  1891. 

1  set  drain  plugs  for  traversing  brack- 
ets. 

1  set   cables   for   electrical   firing  ap- 
paratus. 

*  gross  screws  for  name  and  direction 
plates. 

2  dozen   hexagonal    nuts,   assorted,  U. 
S.  S.,  *  to  1}  inch. 


NOTE. — A  complete  set  of  these  parts  as  far  as  applicable  to  carriages  mounted 
at  any  post  should  be  kept  on  hand. 


20 


In  ordering  parts  of  any  carriage,  always  specify  the  kind,  model, 
and  number  of  carriage  for  which  parts  are  required. 

CONTENTS  OF  COMBINATION  ARMAMENT  CHEST  FOR  FOUR  12-INCH  MORTARS,  CAST 
IRON,  S.  H.,  MODELS  OF  1886  AND  1886  M,  AND  FOUR  12-INCH  S.  R.  MORTAR 
CARRIAGES,  MODEL  OF  1891. 

FOR    MORTARS. 


12  bar  screw-drivers  for  breech  mech- 
anism :  2  for  vent  cover  roller  crank 
and  oil-hole  screws,  2  for  tray  cap, 
tray  back-latch  catch,  and  spring 
bolt  shoe  screws,  2  for  tray  back- 
latch  bolt,  2  for  tray  back  -  latch 
catch  nut,  2  for  lower  pinion  nut,  2 
for  bronze  bushing  crank  lock. 

4  obturator-nut  wrenches. 

4  obturator-nut  clamp-screw  wrenches. 

1  pin  punch. 

4  tit  wrenches  for  obturator  spindle. 
4  pressure  plug  wrenches. 
4  gunner's  quadrants. 

2  bronze  drifts. 

4  gunner's  punches,  for  vent. 

4  cleaning  reamers,  for  primer  seat. 

12  cleaning  brushes,  for  primer  seat. 

4  gunner's  pouches. 

4  pairs  gunner's  sleeves. 

2  bronze  drifts. 

4  gunner's  drills. 

4  boxes  for  firing  mechanism. 

4  gunner's   lanyards. 

4  loading  trays. 

*For  use  on  bruised  breech  blocks 


1  metal   scaper    (for   removing  paint, 
etc.). 

10  pounds  cotton  waste. 
4  balls  twine,   assorted. 

2  pounds  copper  wire,  No.  12. 
2  pounds  copper  wire,  No.  16. 

1  quire  emery  cloth,  No.  00. 
6  wragon  sponges. 

2  files,  flat,  dead  smooth,  8-inch. 
2  files,  round,  second  cut,  8-inch. 
2  files,  half-round,  smooth,  8-inch. 
2  files,  three-cornered,  8-inch. 

1  copper  hammer. 

1  boiler  maker's  hammer. 

1  hand  mallet. 

2  long-handled  mallets. 

1  pair  cutting  pliers,  7-inch. 
1  monkey  wrench,  12-inch. 
1  monkey  wrench,  18-inch,  with  screw- 
driver attachment. 
6  wagon  sponges. 
*3  files,  pillar,  No.  6,  6-inch. 
*3  files,  three-cornered,  No.  4,  6-inch. 
*3  files,  half-round,  smooth,  8-inch. 
*3  files,  round,  smooth,  8-inch, 
no  other  files  to  be  used  thereon. 


FOR  CARRIAGES 


1  spanner  wrench  for  hydraulic  cylin- 
der follower. 

1  spanner  wrench  for  hydraulic  cylin- 
der head. 

1  double  wrench  for  f-inch  and  i-inch 
nuts. 

1  double  wrench  for  f-inch  and  f-inch 
nuts. 

1  single  wrench  for  1-inch  nut. 

1  single  wrench  for  1^-inch  nut. 


1  single  wrench  for  1^-inch  nut. 
1  single  wrench  for  If -inch  nut   (for 
equalizing  pipe). 

The  following  articles  being  too 
chest : 


1  single  wrench  for  1^-inch  nut. 
1  single  wrench  for  If-inch  nut. 
1  single  wrench  for  2-i-inch  nut. 

1  locomotive  oiler,  1  quart. 

2  lifting  bolts  for  stuffing  box  packing 
rings. 

4  lifting  hooks  for  floor  plates. 

2  nut  tighteners,  shot-elevating  screw. 

1  screw  driver,  steel. 

1  screw  driver,  with  wooden  handle. 

2  oilers,  half  pint. 

3  wrenches,  single,  for  filling  plugs. 
1  file  card,  commercial. 

large  are  not  to  be  kept  in  the 


1  wrench  for  lock  nut  on  spring 
pressor  screw. 


com-  I  4  water  buckets,  indurated  fiber. 


21 


LIST    OF    IMPLEMENTS    FURNISHED    WITH    EACH     12-INCH    MOETAB,    MODELS    OF    1886 
AND  1886  M,  AND  S.  R.   MORTAR  CARRIAGES,   MODEL  OF  1891. 


1  rammer  and  stave. 

1  sponge  and  stave,  bore. 

1  sponge  and  stave,  chamber. 

1  breech  cover. 

1  combined  tompion  and  muzzle  cover. 


1  sponge  cover,  bore. 

1  sponge  cover,  chamber. 

1  slush  brush,  with  14-foot  handle. 

1  steel  scraper,  with  14-foot  handle. 

1  special  bore  sponge,  with  stave. 


Weights  of  the  principal  parts  of  the  mortar  carriage,  model  of  1891. 


Name. 


Weight. 


Name. 


Weight. 


•Azimuth  index  ring  (8  sections) 

Azimuth  index  ring  brackets  (8) 

Angle  iron  support  for  floor  plate  (16) 

Base  ring 

Bolts 

Cap  squares 

Cap-square  blocks 

Distance  ring 

Dust  guard 

Elevating  band 

Elevating  gear  bracket  with  parts  at- 
tached  

Elevating  rack 

Elevating-rack  bracket 

Equalizing  pipe,  complete 

Floor  plate,  removable : 

Floor  plates  around  carriage  (16) 

Gun  guides / 

Loading  arm  with  shatt  and  swivel  arm. . 

Pistons  and  rods 

Pit  ladder 

Racer 

Ratchet  wrench 

Recoil  cylinder,  complete,  without  pis- 
ton rod 

Separator  plates  for  springs 

Shell  barrow 

Shell  hoist  scoop 


Pounds. 

2.498 
912 
320 

a  16, 250 
194 

.150 
248 

1,502 
272 
182 

892 

156 

,70 

40 

381 

2,880 

408 

245 

656 

a  119 

o24,500 

22 

1.804 
132 
203 
68 


Shell  hoist  screw  (with  swivel) .. . 

Shell  hoist  screw  handwheel 

Shell  tray 

Shell  tray  false  bottom 

Side  frames % 

Shell  tongs 

Spring  adjusting  screw 

Springs,  coiled 

Spring  cylinder  cap 

Spring  cylinder  extension 

Spring  compression  screw 

Transom 

Traversing  bracket,  lower 

Traversing  crank 

Traversing  pinion 

Traversing  rack 

Traversing  rollers 

Traversing  shaft  (vertical) 

Traversing  shaft  sleeve  (vertical). 

Traversing  worm  wheel 

Trunnion  carriage 

Washers  for  spring  column 

Worm  shaft  bearing  (left  side). ... 
Worm  shaft  bearing  (right  side) . . 

Worm  shaft  with  worm 

Worm  wheel  box 


Total  weight  of  carriage. 


Pounds. 
133 
114 
87 
27 

oll,750 
25 
82 

2,596 

172 

1.170 

154 

o2.335 

166 

36 

165 

1,788 

3,120 

128 

33 

115 

1,806 

100 

80 

114 

135 


82,205 


a  Estimated. 

Names  of  parts  of  12-inch  mortar  carriage,  model  of  1891,  their  location  and 

piece  marks. 


Name  of  part. 


Location. 


Piece 
mark. 


Angle  iron  support 

Azimuth  pointer 

Azimuth  pointer  screw  (brass). 

Base  ring 

Bolts: 

1.25  by  5.25,  with  nuts 

1.25  by  9.25,  with  nuts 

Tap,  1.25  by  3.625 

1.25  by  5.625,  with  nuts 

Tap,  1.25  by  3. 625 

1.5  by  11.,  with  nuts 

Countersunk,  .5  by  1.25 

Countersunk,  1.75  by  2.5... 

Countersunk,  1.5  by  1.1875. 

Tap,  .75  by  1.5 

Tap,  .5  by  1 

Countersunk,  1  by  .875 

Brass  azimuth  strip 

Buffer 

do 

Buffer  iron 

Buffer  rod 

Cap-square . : 

Cover  (buffer) 


Under  floor  plates 

Rear  side  of  upper  roller  path. 

For  azimuth  pointer 

On  platform 


Side  frame  to  cross  transom 

....do 

Side  frame  to  upper  roller  path 

....do 

Cross  transom  to  upper  roller  path. 

Mortar  guides  to  side  frames 

Removable  floor  plate  to  upper  roller  path. 
Guide  for  shot  truck  to  upper  roller  path . . . 

Buffer  covers  to  side  frames 

Pit  ladder 

Lanyard  pulley  bracket 

Plates  to  side  frame  steps 

Screwed  to  index  ring 

For  cross  transom 

For  side  frames 

....do 

For  cross  transom 

Bolted  to  trunnion  carriages 

Fastened  to  side  frames 

Between  side  frames . . . 


Cross  transom 

Distance  block On  mortar  guides 

Drain  plug Equalizing  pipe  return  elbow 

Elbow Equalizing  pipe 


22 

Names  of  parts  of  12-inch  mortar  carriage,  model  of  1891,  etc. — Continued. 


Name  of  part. 


Location. 


Piece 
mark. 


Elevating  mechanism,  consisting  of: 

Elevating  rack 

Elevating  'gear 

Bracket  (right  and  left) 


Bushing 

Brace 
Bolts: 

Stud,  .1  by  4.,  with  nuts 

Tap,  1  by  1  .875 

Tap,  .75  by  3.25 

Tap,  .1  by  3.5 

Tap,  .75by  2.5  ..............  , 

Countersunk,  .75  by  2.5 

.875  by  3.125,  with  nuts 

.375  by  1  .25  (round  head) 
Direction  plate 
Distance  piece 
Elevating  pinion  and  shaft 
Handwheel 
Index  (elevating  gear) 
Key 
Mortar  band  ................ 

Nut  ...... 

Pinion 

Screw  (brass) 

Set  screw  (pointed)  .75  by  1.25... 

Shaft  ......... 

Washer 

Washer  ........... 

Equalizing  pipe 

Eye  screw 

Floor  plate 

Floor  plate  (removable) 

Guide  bar 

Index  ring,  8  sections  (azimuth) 

Index  ring  (azimuth) 

Loading  position  latch,  consisting  of: 

Latch  handle 

Bolt 

Bolt,  tap 

Connectng  rod  ............ 

Handle  fulcrum  .......  ....... 

Pawl 

Pawl  spring 

Pawl  plate 

Pawl  fulcrum 

Pawl  bracket 


One  on  each  side  of  mortar 

On  elevating  gear  shaft 

For  elevating  gear  shaft  (on  trunnion  car- 
riage). 

On  trunnion  carriages 

For  elevating  racks 


Elevating  brackets  to  trunnion  carriages. 

Brace  for  elevating  rack  to  mortar 

Distance  pieces  to  mortar  band 

Distance  pieces  to  mortar 

Elevating  rack  to  distance  pieces 


.do. 


Elevating  rack  to  braces 

Index  finger  to  elevating  racks . 

On  handwheels 

Elevating  racks 


12A. 
12B. 


On  handwheel  shaft 

On  trunnion  carriages 

Elevating  gear  brackets 

Shrunk  on  mortar 

Handwheel  shaft 

For  elevating  handwheels 

Direction  plates 

Bracket  for  elevating  screw 

For  elevating  handwheels 

E  levating  shaft t 

Handwheel  shaft 

Between  recoil  cylinders 

Cap-square  for  trunnion  carriages. 

Bolted  to  angle  iron  supports 

On  upper  roller  path 

On  Qoor  plate 

Bolted  to  bracket 

On  base  ring 


Screw,  countersunk  ..................  . 

Spring  plunger  ................... 

Split  pin  ............................  . 

Steel  washer  ........  .  ................  , 

Mortar  guide  ............................  , 

Mortar  stop  ..............  .  ...............  , 

Nipple  ..................................  , 

Nut... 


Handle  fulcrum 33D1 

Pawl  plate 33E 

Pawl  bracket 33C 

do 33P 

Elevating  bracket,  right 33G 

Pawl  bracket 33A 

In  spring  plunger . 

Elevating  bracket,  right 33M 

Pawl  bracket 33L 

Elevating  bracket,  right 33K 

Pawl  fulcrum !  Q3C 

On  connecting  rod !  33N 

Pawl  plate \  33F 

Pawl  bracket i  33J 

On  handle  fulcrum 


.do. 


33B 


....do  ................................... 

Oil  pipe  ................................. 

Oil  pipe  strap  ...........................  , 

Oil  pipe  bracket  .........................  , 

Oil  plug  .................................  . 

Packing  ring  ............................  . 

Pit  ladder  ...............................  , 

Recoil  system,  consisting  of: 

Hydraulic  cylinder  (right  and  left)  .  .  . 

Belleville  spring  (pair)  (steel  mortar)  . 

Bushing  (piston)  ..................... 

Bushing  .  .  .  .......................... 

Bushing  .............................. 

Bushing  .............................. 

Buffer  (balata)  ......................  . 

Buffer  (iron)  ........................  . 

Bolts— 

1.5  by  10.375,  with  nuts  ..........  . 

1.5  by  5.25,  with  nuts  ............ 

1.25  by  5.375,  with  nuts  .......... 

Stud,  1.25  by  5.25,  with  nuts  ..... 


To  distance  blocks 

On  cross  transom 

Equalizing  pipes 

For  nipples 

For  equalizing  pipe  rod. 
On  upper  roller  path . . . 


.do. 


Screwed  to  upper  roller  path . 

In  oil  pipe 

In  trunnions 

Bolted  to  upper  roller  path. ., 


On  side  frames 

In  each  cylinder 

Forged  on  piston 

Lower  end  of  each  cylinder. . . 
At  top  of  springs  in  cylinders. 
Trunnion  carriages 


Stud,  1.5  by  5.75,  with  nuts. 
Tap,  1  by  2.25 
Countersunk,  0.5  by  1.5 


Hydraulic  cylinder  to  side  frames 

Hydraulic  cylinder  to  spring  cyl.  extension 

Spring  cylinder  extension  to  side  frames 

.do. 


Spring  cylinder  caps 

Supporting  bracket  to  spring  cyl.  extension. 
Inside  liners  to  trunnion  carriages 


23 

Names  of  parts  of  12-inch  mortar  carriage,  model  of  1891,  etc. — Continued. 


Name  of  part. 


Location. 


Piece 
mark. 


Recoil  system,  consisting  of— Continued. 

Cover  plate 

Dowel  pins,  0.75  by  3 

Felt  strip 

Grease  cup 

Follower 

Key  with  split  pin 

Handy  oiler 

Liner 

Plate 

Plug  (throttling),  with  leather  washers. 

Pipe  plug,  2- inch,  with  leather  washers 

Pipe  plug,  1 .5-inch,  with  leather  washer . 

Piston  rod 

Spring  compression  screw 

Spring  compression  bolt,  with  4  nuts.. 

Spring  cylinder 

Spring  cylinder  cap 

Spring  separator  plate 

Spiral  spring  (double  coil)  (cast-iroh 
mortar). 

Spiral  spring  (double  coil)  (steel  mortar) 

Top  head,  with  leather  washer 

Trunnion  carriage  (right  and  left) 

Spring  cylinder  extension  (left  and 
right). 

Supporting  bracket 

Washer 

Washer  and  top  plate 

Return  ell 

Screw  (orass) 

Screw  (countersunk,  bronze) 

Separator 

Side  frame  (left  and  right) 

Traversing  mechanism,  consisting  of: 

Bracket  (worm  shaft) 

Bracket  (vertical  shaft) 

Bronze  bushing 

Do 

Do 

Cover 

Crank 

Bolts— 

.25  by  6. 125,  with  nuts 

.25  by  4.625,  with  nuts. . . 

.25  by  4.375,  with  nuts 

1.25  by  6.,  with  nuts 

.35  by  5.25,  with  nuts 

.125  by  14.75,  with  nuts 

.25  by*  4.25,  with  nuts 

.5  by  11.,  with  nuts 

0.375  by  0.875,  with  nuts 

0.625  by  0.75 

Countersunk,  0.375  by  1.25 


On  trunnions 

Supporting  bracket  to  spring  cyl.  extension. 

On  cover  plates 

In  trunnion  carriages 

Two  in  each  cylinder 

On  upper  end  of  piston  rods 

In  trunnion  (plate  covers) 

Trunnion  carriages 

At  each  end  of  spiral  springs 

In  hydraulic  cylinders 


Used  to  assemble  recoil  springs. . 
do. 


Cast  on  side  frames 

Bolted  to  spring  cylinders 

Against  end  of  each  end  of  spiral  s 
In  each  spring  cylinder 


.do. 


Hydraulic  cylinders. 

In  spring  cylinders 

[Side  frames 

I  Bolted  to  side  frames 

Bolted  to  spring  cylinder  extensions. 

For  spring  compression  screws 

In  spring  cylinders. 


Connecting  equalizing  pipes. 
Supports  equalizing  pipes. . . 
Oil  pipe  bracket  and  strap . . . 

Removable  floor  plate 

Cross  transom  buffer , 

Bolted  to  upper  roller  path.. 


Bolted  to  side  frames 

Inner  side  of  right  side  frame. 

In  worin  box 

In  bracket  for  worm  shaft  — 
In  bracket  for  vertical  shaft . . 

On  worm  box 

On  worm  shaft 


Worm  box  to  side  frames 

....do 

Left  bracket  for  worm  shaft 

Lower  traversing  bracket  to  upper  roller  path 
.do. 


Tap,  0.5  by  1. 

Tap,  0.75  by  2.375... 

Tap,  0.875  by  2.125.. 

Tap,  1.25  by  2.75... 

Tap,  1.25  by  4.75... 

Distance  rings,  set 

Dust  guard  pipe 

Dust  guard  (4  sections) . 

Handle 

Oil  tube 

Oil  plug 

Pinion. 


Separator  bolts  in  distance  rings. 

Joints  in  traversing  circle 

Joints  in  distance  rings, 

Joints  in  dust  guard 

Traversing  pointer  to  upper  roller  path 

Cover  to  worm  box 

Dust  guard  to  upper  roller  path 

Traversing  rack  to  lower  roller  path 

Bracket  for  worm  shaft  to  worm  box 

Right  bracket  for  worm  box. .' 

Worm  box  to  side  frame 

Support  traversing  rollers 


Separator 

Shaft  (horizontal) 

Split  pin,  0.25 

Traversing  roller 

Traversing  rack 

Traversing  circle  (8  sections). 

Traversing  pointer 

Upper  roller  path 

Vertical  shaft 

Worm 

Worm  box 

Worm  wheel 


On  upper  roller  path 

On  traversing  cranks 

Traversing  worm  shaft  bracket. 

On  miscellaneous  parts 

On  vertical  shaft 

Between  distance  rings 

Between  side  frames 

In  vertical  shaft 

Maintained  in  distance  rings . . . 

On  base  ring 

On  upper  roller  path 

Upper  roller  path 

On  traversing  rollers 

Through  bracket  on  racer 

On  horizontal  shaft 

On  right  frame 

On  vertical  shaft 


24 


Names  of  parts  of  12-inch  mortar  carriage,  model  of  1891,  their  location  and 

piece  marks. 

SHOT  TRUCK,  TYPE  12  ME. 
[One  truck  for  each  carriage.] 


No. 

Name  of  part. 

Location. 

Piece 
mark. 

1 

Axle 

Frame 

N25D 

1 

Axle  bracket  (left) 

do 

35B 

1 

Axle  bracket  (right) 

do  

35  A. 

4 

Bolts 

Cylinder  filler  piece  to  frame 

N19K 

4 

Do... 

Brake  shaft  bracket  to  frame  

N24E. 

4 

Do 

Buffer  cylinder  to  frame 

N19B. 

3 

Do... 

Detachable  rim  to  caster  wheel  

A48X. 

10 

Do 

Detachable  rim  to  truck  wheel  

A48A. 

1 

Bracket 

On  frame 

N24A. 

1 

Brake  shaft.      .      .         

Brake  shaft  brackets  

N24G. 

0 

Brake  shaft  bracket 

Frame  

N24D. 

1 

Brake  lever 

do 

35F. 

9 

Brake  shoe 

Brake  shaft                

N24F. 

1 

Buffer  cylinder 

On  frame 

N19A. 

? 

Bushing 

Truck  wheel  

A48H. 

1 

Do 

Caster  wheel                          ..._.. 

A48R. 

1 

Cap  

Piston  rod  

N19H. 

1 

Caster 

Bracket.                 

N24C. 

1 

Caster  whejel  

Rear  of  truck  ^ 

A48P. 

1 

Caster  wh6el  pin 

Caster  wheel  

N25B. 

1 

Cylinder  filler  piece 

On  frame                          ..         

N19J. 

I 

Cylinder  head 

Buffer  cylinder 

N19F. 

1 

Collar 

Caster                        

N24B. 

2 

Detachable  rim 

Truck  wheel 

A48G. 

1 

Do 

Caster  wheel  

A48Q. 

1 

Frame  complete 

On  axle                               

2 

Buffer  cylinder 

N19C. 

1 

Gasket 

Cylinder  head                  

1 

Name  plate 

On  frame 

A3C. 

2 

Nuts  crown 

On  axle  .            

1 

Handle 

Handle  bands                          .     ... 

N25A1. 

9 

Arms  

N25C1. 

2 

Handle  clamp 

.do                                

N25H1. 

9 

Oil  plugs 

Truck  wheel  hubs  

QC3. 

I 

Do    

Caster  wheel  hubs    

QC3. 

* 

g 

Packing  rings 

Cylinder  head 

j 

Buffer  cylinder 

35H. 

1 

Pin 

Piston  and  rod                   

Do 

Cap  to  piston  rod  

Pin  taper  with  split  pin 

Collar  to  caster    

Do.  ..              

Brake  shoes  to  brake  shaft  

Pin.  taper 

Axle  

'DO 

Axle  brackets                 

Pin  taper  with  split  pin 

Brake  lever                                        .      ... 

1 

Rod*  guide* 

35G. 

? 

Screws     

Handle  clamp  

N25J1. 

1 

Shot  tray 

Frame 

35C. 

1 

Shot  tray  end 

Shot  tray                     

35D. 

1 

Stop                                                  .... 

Frame  

N25G. 

1 

Shot  tray 

35E. 

2 

Tire 

Truck  wheel                         

A48J. 

1  i 

Do 

Caster  wheel  

A48S. 

1 

Tray  support 

N25F. 

2 

Truck  wheel 

Truck                                               

A48F. 

0 

Washer 

Filling  and  drain  plug  

2 

Do 

Axle                        

N25E. 

WAR  DEPARTMENT, 

OFFICE  OF  THE  CHIEF  OF  ORDNANCE, 

Washington,  April  21,  1917. 

April  19, 1904. 

Revised  December  22, 1909. 

Revised  April  21, 1917. 

FOKM  No.  1698. 

Ed.  Apr.  21, 17—500. 


fc 


GENERAL  METHOD  OF  CONTROLLING  THE  ENERGY 
OF  RECOIL  IN  MORTAR  CARRIAGES. 


fc 


WASHINGTON  :  GOVERNMENT  PRINTING  OFFICE  :  1911 


YC  64343 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


